The invention pertains to digital data processing and, more particularly, to methods and apparatus for improving the processing power, ruggedness and/or longevity of digital data processing systems. The invention has application, by way of non-limiting example, in high-density embedded computer systems for image and signal processing applications such as radar, sonar, medical data acquisition and imaging, semiconductor device inspection and imaging, to name a few.
As processor speeds and circuit board densities increase, heat has become the limiting factor in computer design. Unless adequately dissipated, it can cause computers to run unpredictably or to crash. Excessive heat also substantially reduces component lifetimes. While this is merely annoying to the typical home or business user, it can prove catastrophic in mission critical applications, such as medical imaging, surveillance, and so forth.
The power requirements of reasonably sized individual computer circuit boards appear to be reaching asymptotic limits. Not so of the computers that house them. Manufacturers of at least high-end computer systems are pressured to include ever more circuitry in ever smaller chassis in order to meet customer throughput, redundancy and space requirements. The latter presents a real conundrum, however, since higher density board stacking reduces throughput and reliability, necessitating still more boards.
While cooling computer systems—and, particularly, for example, high density systems which now consume up to 3000 watts per cubic foot—can be accomplished using low temperature fluids or special gases, forced air-convection cooling remains the preferred mechanism. The dilemma of using this choice is compounded where inlet operating temperature requirements for some systems, for example, high-density embedded systems, is typically 50%-55° C., extending up to 70° C. in some cases.
Holding junction temperatures to acceptable levels for meeting the required reliability with these high inlet temperatures is at best difficult, and at worst impossible, using prior art techniques. This is likewise true of maintaining basic component operation temperatures of 85°-100° C. Moreover, many of these systems are placed in close proximity to people, so the noise-levels must typically be at or below 65-68 dB(A) at 1 meter.
An object of this invention is to provide improved methods and apparatus for digital data processing.
A more particular object is to provide such methods and apparatus as improve the capacity, density, efficiency, ruggedness, and/or longevity of such digital data processing systems.
Another object of the invention is to provide such methods and apparatus as can be used with air-cooling and move particularly, for example, forced air-cooling—as well as with other heat dissipation techniques.
Still other objects of the invention are to provide such methods and apparatus as can be implemented at low cost using existing components, materials and/or fabrication techniques.